The present invention relates to a device designed to protect a shaft or the like from exposure to excessive torque. More particularly, the present invention relates to torque-override devices designed to disengage a first shaft portion from a second shaft portion when excessive rotational torque is applied to the shaft. Still more particularly, the present invention relates to a winch assembly with a torque-override shaft.
It is recognized that torque-control mechanisms for rotatable shafts and similar devices are important in extending the lifetimes of such devices. For example, fuel caps may include torque-control mechanisms for preventing users from overtightening the caps. The caps typically include an outer shell and a closure member. The user grips and rotates the outer shell to rotate and advance the closure member in a filler neck or the like. Some devices have used pawl-and-ratchet arrangements in which the pawl disengages from the ratchet when the outer shell of the cap is overtightened, thus disconnecting the outer shell from the closure member. See, for example, U.S. Pat. No. 4,913,303 to Harris. Other devices include a plurality of drive teeth mounted directly on the outer shell for camming engagement with a ratchet wheel or the like including a plurality of driven teeth. Under excessive rotation, the drive teeth disengage from the driven teeth to disconnect the outer shell from the closure member. See, for example, U.S. Pat. No. 5,110,003 to MacWilliams.
Torque-override mechanisms have also been used to prevent users from overstressing rotatable shafts. In a shaft having a crank or other first portion to be rotated by a user and a second portion, the torque-override mechanism may be positioned between the first and second portions to disengage the second portion from the first portion when a user applies excessive rotation to the first portion.
Such a situation might typically arise, for example, in use of a winch assembly. See, for example, U.S. Pat. No. 5,188,341 to Greaves. A winch assembly for raising or lowering a spare tire mounted on the underside of small vans or other comparable vehicles may be particularly susceptible to damage from excessive torque. A mechanic using a torque wrench or other power tool may inadvertently apply excess torque to the winch shaft, stressing or possibly even breaking the shaft. A properly designed torque-override apparatus can remedy this problem. Thus, there is a particular need for a torque-override assembly which can be easily integrated with a winch assembly in a sturdy, reliable system.
According to the present invention, a torque-limited winch assembly is provided. The torque-limited winch assembly includes a winch, a winch housing, a torque-override assembly, a shell for the torque-override assembly, and means for retaining the shell in engagement with the winch housing to provide an integrated assembly. The torque-override assembly includes a drive hub, a driven hub, and a spring biasing the drive hub into torque-limited engagement with the driven hub. The shell includes a radially-extending peripheral rim, and the retaining means retains the peripheral rim in engagement with the wall of the winch housing.
In preferred aspects of the present invention, the retaining means advantageously includes an axially-extending circular flange including a plurality of retaining tabs to engage and retain the peripheral rim. In further preferred aspects of the present invention, the drive hub includes a plurality of drive teeth, each including first and second ramped drive faces, and the driven hub includes a plurality of driven teeth. Each driven tooth includes a first ramped driven face to provide the torque-limited connection for clockwise rotation and a second ramped driven face to provide the torque-limited connection for counterclockwise rotation.
Further according to the present invention, the winch assembly includes a torque-override assembly, a winch, and a housing including a first housing component defining a first chamber for the torque-override assembly and a second housing component defining a second chamber for the winch. The first housing component includes a first cup-shaped wall and a radially-extending circumferential rim. The second housing component includes a second wall and an axially extending circular flange including a plurality of retaining tabs to engage the circumferential rim so that the first housing component is affixed to the second housing component.
Yet further according to the present invention, the winch assembly includes a torque-override assembly, a winch, and a housing including a first housing component defining a first chamber for the torque-override assembly and a second housing component defining a second chamber for the winch. The first housing component includes a first cup-shaped wall and the second housing component includes a second wall. The housing further includes means for fastening the first housing component to the second housing component. In one preferred aspect of the invention, the first fastening means includes a radially-extending circumferential rim. In another preferred aspect of the invention, the second fastening means includes a plurality of retaining tabs to engage the first fastening means.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.